The objective of this grant is the preparation and application of monoclonal antibodies to the characterization of mouse interferon. During the first year of the study, the goals were to optimize the hybridization technique and immunization schedule and to standardize a screening assay for anti-interferon antibodies in hybrid supernatants. To this end, we have screened two lots of polyethylene glycol and 13 lots of fetal calf serum and have increased our average frequency of hybrid formation from 5% to 50%. We have also determined that: 1) only certain strains of rats produce anti-mouse IFN antibodies (i.e., DA and ACI); 2) four weekly s.c. inoculations of 10 to the 5th power units of IFN are sufficient to induce anti-IFN antibodies in ACI rats; and 3) Freund's complete adjuvant does not significantly enhance anti-IFN antibody production. Therefore, ACI rats will be given four inoculations of 10 to the 5th power units of mouse IFN at weekly intervals, will be rested 3 to 4 weeks, will then be given an i.v. boost of 10 to the 5th power units of IFN, and will be sacrificed 2 to 3 days later in order to use their spleen cells for hybridization. Our primary objectives during the second year of this grant are to complete standardization of an ELISA assay for detection of anti-IFN antibodies in hybrid supernatants and to obtain monoclonal anti-mouse IFN antibodies.